1. Field of the Invention.
The invention in general relates to electromechanical timers having combination electrical terminals and switchblades and more particularly to the manner of securing the electrical terminal-switchblade combinations in such timers.
2. Description of the Related Art.
The use of electromechanical timers for providing programmed control of functions of appliances is well-known. Such electromechanical timers generally include a motor-driven cam and electrical switches responsive to the cam for controlling the programmed functions. The cam and switches are supported in a housing, and terminals electrically connected to the switches are mounted on and extend from the housing to provide for electrical connection to a power source and the appliance components to be controlled. To provide repeatability of timing functions and timer integrity over the long periods over which it is expected that the timer will operate, it is essential that both the terminals and the switches be firmly secured in the housing within relatively small tolerances. It has been recognized for many years that this objective is most economically met by providing the terminals and switchblades in a single unit, which allows both to be secured to the housing at one time. There is extensive art relating the manner of securing such electrical terminal-switch blade combinations in timers. U.S. Pat. No. 3,390,243 in the name of George Obermann shows two such methods. The blades may be molded into a wafer which is then secured in the housing as depicted in FIG. 4, or the blade may be formed with a ramp terminating in a stop combined with a second stop as shown in FIG. 11. The first method provides for very secure blades but requires additional manufacturing steps. The latter method either does not provide as secure a fixation as required for the switchblades, or it requires very accurate control of tolerances, which is very expensive. U.S. Pat. Nos. 4,734,548 on an invention of Ronald E. Cole and 3,727,015 on an invention of Elmo W. Voland, Harold T. Simmons, and Pauker Kurt show two variations on another manner of securing the terminal-switchblade combination in electromechanical timers. In these timers, the terminals are placed in slots in the body of the housing and a cover is closed over the slots. Motion of the blades along the direction of the slots through the housing body wall is prevented by projections lanced in the blade which engage notches in the housing. This method has been found to hold the blades firmly, however it also requires a number of separate manufacturing steps. In a timer made by Eaton Corporation of Cleveland, Ohio, two ramped lances are formed in the blade to form two separate stops which engage notches or cavities that communicate with a slot in the housing. The terminal is inserted into the slot in a single operation, and the ramped surface of the lances forcing the lance to enter the plane of the slot while passing through it, and the ramps pop out when they reach the notches or cavities to provide a stop. Stability is provided by separating the two lances, one being located near one end of the slot and the other being near the other. In this timer, the switchblades are attached at right angles to the terminal blades to provide further stability. This latter construction permits an insertion of the blades in one operation, but requires a relatively complex blade and housing structure and close control of tolerances for the blades to be stable. All of the above methods require a relatively thick housing body (0.5 inches or more) in the area where the blades attach. In another common method of blade fixation the blades are formed with a thinner portion and a wider shoulder portion. Each blade is inserted into a slot in the housing until the shoulder engages the housing and stops the movement, and the other end of the blade is then staked to secure the blade to the housing. See U.S. Pat. No. 4,841,496 on an invention of George W. Adams, Steven W. Smock, and Ross G. Helft. This method holds the blades firmly in a relatively thin housing body, but requires a number of manufacturing operations.